Economic analysis of treating depression with nefazodone v. imipramine

Economic considerations in the prescribing of third-generation antidepressants

A comprehensive, multinational literature search was conducted of all articles published from 1993 to 2003 regarding the cost effectiveness of antidepressant drugs, with special emphasis on comparing third-generation antidepressants (TGAs) with tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs). Information from the collected articles was entered into a database and then analysed to assess the different approaches to cost effectiveness comparisons for the various classes of antidepressants. Factors examined included direct and indirect costs, treatment endpoints, healthcare cost burden and productivity gains for patients successfully treated for depression. Most model-based studies published between 1993 and 2003 supported the cost effectiveness of TGAs compared with TCAs or SSRIs. While the purchase price of TGAs may be greater, cost savings in terms of direct and indirect costs were realised because of the reduced adverse effects of TGAs and subsequent improved patient compliance. Studies based on patient level cost data, however, were less conclusive about the economic benefits of TGAs compared with SSRIs or TCAs. While it may be premature to conclude that TGAs have a significant net economic benefit compared with other antidepressant classes, prescribers and payers may find it helpful when choosing antidepressants for depressed patients to consider that the higher drug prices for TGAs may be offset by savings, in terms of their greater compliance and resultant therapeutic success rates compared with TCAs or SSRIs. Additional research is needed to clarify how cost effectiveness is assessed in different patient populations, such as geriatric patients--who commonly have more co-morbidities and higher total healthcare costs than other patient populations.

Quantitative analysis of sponsorship bias in economic studies of antidepressants

BACKGROUND

Concern is widespread about potential sponsorship influence on research, especially in pharmacoeconomic studies. Quantitative analysis of possible bias in such studies is limited.

AIMS

To determine whether there is an association between sponsorship and quantitative outcomes in pharmacoeconomic studies of antidepressants.

METHOD

Using all identifiable articles with original comparative quantitative cost or cost-effectiveness outcomes for antidepressants, we performed contingency table analyses of study sponsorship and design v. study outcome.

RESULTS

Studies sponsored by selective serotonin reuptake inhibitor (SSRI) manufacturers favoured SSRIs over tricyclic antidepressants more than non-industry-sponsored studies. Studies sponsored by manufacturers of newer antidepressants favoured these drugs more than did non-industry-sponsored studies. Among industry-sponsored studies, modelling studies favoured the sponsor's drug more than did administrative studies. Industry-sponsored modelling studies were more favourable to industry than were non-industry-sponsored ones.

CONCLUSIONS

Pharmacoeconomic studies of antidepressants reveal clear associations of study sponsorship with quantitative outcome.

The economics of selective serotonin reuptake inhibitors in depression: a critical review

The prevalence of depression and the high costs associated with its treatment have increased interest in pharmacoeconomic evaluations of drug treatment, particularly in the 1990s as the use of selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs) expanded substantially. This review presents results from specific studies representing the key study designs used to address the pharmacoeconomics of SSRI use: retrospective administrative database analyses, clinical decision analysis models, and randomised clinical trials. Methodological considerations in interpreting results are highlighted. In retrospective administrative database analyses, most comparisons have been made between SSRIs and tricyclic antidepressants (TCAs). A few studies have addressed differences between SSRIs. The studies focused on healthcare cost (to payer) and cost-related outcomes (e.g. treatment duration, drug switching). Although SSRIs are generally associated with higher drug acquisition costs than are TCAs, total healthcare costs are at least offset, if not decreased, by reductions in costs associated with use of SSRIs. Although studies from the early 1990s show some advantage for fluoxetine, the results are limited by use of data from shortly after the introduction of paroxetine and sertraline; studies from the mid- 1990s on that compare drugs within the SSRI class show general equivalence in terms of cost. Important methodological advances are occurring in retrospective studies, with selection bias and other design limitations being addressed statistically. Clinical decision analysis models permit flexibility in terms of ability to specify different alternative treatment scenarios and varying durations. Sensitivity analysis aids interpretability, although model inputs are limited by data availability. Results from short term (1 year duration or less) studies comparing SSRIs and TCAs suggest that SSRIs are more cost effective or that there is no difference. Longer term studies (lifetime Markov models) focus more on the impact of maintenance antidepressant therapy and show more mixed results, generally favouring SSRIs over TCAs. The results indicate that the effect of SSRIs is mainly through prevention of relapse. Important assumptions of these models include fewer serious adverse effects and lower treatment discontinuation rates with SSRIs. Naturalistic clinical trials provide greater generalisability than traditional randomised clinical trials. One naturalistic trial found that nearly half of TCA-treated patients switched to another antidepressant within 6 months; only 20% of SSRI-treated patients switched. Cost differences between groups were minimal. These studies indicate few differences in medical costs, depression outcomes and health-related quality of life between TCAs and fluoxetine, although fewer fluoxetine-treated patients switched treatment.

Formulary restriction of selective serotonin reuptake inhibitors for depression: potential pitfalls

The American healthcare market is currently estimated at more than 900 billion US dollars with double digit rising costs per year. Psychotropic agent costs have more than kept pace with market increases. Medication acquisition costs are an obvious focus for limiting costs in various care systems. Restrictive formularies are a common method of attempting to limit costs. To support our opinion that a single agent is ill advised, we explored the available evidence on the intended and unintended consequences of having a single or exclusive selective serotonin reuptake inhibitor (SSRI) on a formulary. Central to this position is an assumption of the interchangeability of SSRIs; we examined the evidence for and against this through a model to determine the probability of interchangeability. We conclude that the practice of having a single SSRI on the formulary for a healthcare plan seems ill founded. Patients who switch antidepressants remain in treatment 50% longer and cost approximately 50% more to treat in a more costly treatment setting. Giving the primary care physician several antidepressant choices can provide more options to continue treatment of his or her patient in the less expensive primary care setting. In terms of cost containment, formulary restrictions are far more likely to have the opposite effect.

Economic impact of using mirtazapine compared to amitriptyline and fluoxetine in the treatment of moderate and severe depression in the UK

This study modelled the economic impact of mirtazapine, compared to amitriptyline and fluoxetine, in the management of moderate and severe depression in the UK, as well as the costs related to discontinuation of antidepressant treatment. Decision models of the management of moderate and severe depression were developed from clinical trial data, resource use obtained from interviews with general practitioners and psychiatrists, and published literature, and were used to estimate the expected direct National Health Service (NHS) costs of managing a patient with moderate or severe depression. The expected cost of healthcare resource use attributable to managing a patient suffering from moderate or severe depression who discontinues antidepressant treatment, irrespective of the initial treatment, was estimated to be pounds sterling 206 (range pounds sterling 50 to pounds sterling 504) over five months. Using mirtazapine instead of amitriptyline for seven months increases the proportion of successfully treated patients by 21% (from 19.2 to 23.2%) and reduces the expected direct NHS cost by pounds sterling 35 per patient (from pounds sterling 448 to pounds sterling 413). Using mirtazapine instead of fluoxetine for six months increases the proportion of successfully treated patients by 22% (from 15.6 to 19.1%), albeit for an additional cost to the NHS of pounds sterling 27 per patient (from pounds sterling 394 to pounds sterling 420). In conclusion, this study suggests that mirtazapine is a cost-effective antidepressant compared to amitriptyline and fluoxetine in the management of moderate and severe depression in the UK.

The need for an iterative process for assessing economic outcomes associated with SSRIs

Pharmacotherapeutic advances in the treatment of depression have included the development of the selective serotonin reuptake inhibitors (SSRIs), thereby providing alternatives to tricyclic antidepressants. Concurrent with these events have been significant structural (e.g. pharmaceutical formularies) and regulatory (e.g. required pharmacoeconomic evaluations) changes in the delivery, financing, and oversight of healthcare programmes throughout the world. International cost-containment initiatives are increasingly mandating a demonstration of value for money, defined in terms of a measurable health and/or financial outcome, and, in the case of medicines, attributable to a given expenditure, for a given pharmacotherapeutic option. We examine the inherent strengths and weaknesses of 5 study designs used to discern and contrast financial outcomes stemming from the use of antidepressant pharmacotherapy for the treatment of depressive illness [randomised controlled trials (RCTs); meta-analyses; decision-analytical models (DAMs); retrospective database investigations; randomised naturalistic inquiry]. We argue that the economic appraisal of pharmacotherapy requires an iterative process extending from the developmental (RCTs; meta-analyses; DAMs) through to the postmarketing phase (database reviews; naturalistic inquiry), thereby resulting in a portfolio of evidence as to the safety, efficacy and effectiveness of a given pharmacotherapeutic category (e.g. SSRIs) and/or a specific medication. Database reviews, while nonrandomised, and prospective naturalistic inquiry afford greater insight into the patterns of use and financial merits of prescribing specific pharmacotherapeutic options for the treatment of depression within the context of clinical practice as compared with RCTs, meta-analyses and DAMs. The portfolio of evidence to date indicates that the first-line use of SSRIs in the treatment of depression is clinically warranted, and represents value for money.

Nefazodone. A review of its pharmacology and clinical efficacy in the management of major depression

Nefazodone hydrochloride is a phenylpiperazine antidepressant with a mechanism of action that is distinct from those of other currently available drugs. It potently and selectively blocks postsynaptic serotonin (5-hydroxytryptamine; 5-HT) 5-HT2A receptors and moderately inhibits serotonin and noradrenaline (norepinephrine) reuptake. In short term clinical trials of 6 or 8 weeks' duration, nefazodone produced clinical improvements that were significantly greater than those with placebo and similar to those achieved with imipramine, and the selective serotonin reuptake inhibitors (SSRIs) fluoxetine, paroxetine and sertraline. The optimum therapeutic dosage of nefazodone appears to be between 300 and 600 mg/day. Limited long term data suggest that nefazodone is effective in preventing relapse of depression in patients treated for up to 1 year. Analyses of pooled clinical trial results indicate that nefazodone and imipramine produces similar and significant improvements on anxiety- and agitation-related rating scales compared with placebo in patients with major depression. Short term tolerability data indicate that nefazodone has a lower incidence of adverse anticholinergic, antihistaminergic and adrenergic effects than imipramine. Compared with SSRIs, nefazodone causes fewer activating symptoms, adverse gastrointestinal effects (nausea, diarrhoea, anorexia) and adverse effects on sexual function, but is associated with more dizziness, dry mouth, constipation, visual disturbances and confusion. Available data also suggest that nefazodone is not associated with abnormal weight gain, seizures, priapism or significant sleep disruption, and appears to be relatively safe in overdosage. Nefazodone inhibits the cytochrome P450 3A4 isoenzyme and thus has the potential to interact with a number of drugs. Further long term and comparative studies will provide a more accurate assessment of the relative place of nefazodone in the management of major depression. Nonetheless, available data suggest that nefazodone is a worthwhile treatment alternative to tricyclic antidepressants and SSRIs in patients with major depression.